Mark done (multi), remove preStr, Set enddate to "999999" if not enter by user

Undo still have problem for edit, mark. it works with add, delete,
sort,clear, search.
Merge remote-tracking branch 'origin/master'
unignore
unignore logic.java
Merge remote-tracking branch 'origin/master' into Qingtao_Add/Delete/Undo
Put back Logic after github accident
Merge remote-tracking branch 'origin/master' into Qingtao_Add/Delete/Undo
Recommit Mark
Merge remote-tracking branch 'origin/khye-an'